The present invention relates to a short-circuit device which is reversible by recoiling. The invention also relates to the use of the short circuit in a photoelectric tube provided with a photocathode and having a Joule effect evaporator of a material constituting the photocathode.
The technical problem to be solved with any short-circuit which is reversible by recoiling, notably remotely reversible short-circuits, is to obtain a device which is not very bulky, is inexpensive and, above all, is reliable in the sense that the short-circuit can be reversed with great reliability. French Patent Specification No. 81 22 380 describes a short-circuit which reversible by recoiling and is constituted by a fusible conductor wire which is subjected to tensile stress a tensile force and which breaks after fusion by heating by means of a high frequency radiation. This known short-circuit has the advantage of having small dimensions and being inexpensive. However, it has proved to have insufficient reliability with too weak heating and due to the difficulty of obtaining a reproducible tensile force.
The general technical problem to be solved by the present invention is to realize a short-circuit which is reversible by recoiling, is inexpensive, is not bulky and is reliable, notably when remotely reversed by means of a high-frequency radiation. An advantageous embodiment of the short-circuit according to the invention comprises a photoelectric tube provided with a photocathode and having a Joule effect evaporator of a material constituting the photocathode and at least two dynodes each held at an electric potential via polarization conductors. The present Application propounds as its particular technical problem to be solved the capability of using the conductors of the dynodes to evaporate, by the Joule effect, the material constituting the photocathode without increasing the number of lead-throughs in the base of the photoelectric tube.